asset

package
v1.0.0 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Jul 24, 2026 License: MIT Imports: 28 Imported by: 0

Documentation

Overview

Package asset handles CSS/JS bundling, image optimization, and content-hashed asset pipelines.

Index

Constants

This section is empty.

Variables

View Source 
var ErrAVIFNotAvailable = errors.New("AVIF encoding not available: rebuild with -tags avif")

ErrAVIFNotAvailable is returned when AVIF encoding is requested but the build was not compiled with the avif build tag. Declared in an untagged file so both build modes compile (image.go references it unconditionally).

Functions

func Fingerprint 

func Fingerprint(data []byte) string

Fingerprint computes a content hash for the given data. Returns the first 8 hex characters of the SHA-256 hash.

func FingerprintFile 

func FingerprintFile(path string) (string, error)

FingerprintFile reads a file and returns its content fingerprint.

func FingerprintedName 

func FingerprintedName(name, hash string) string

FingerprintedName inserts a hash into a filename before the extension. Example: FingerprintedName("main.css", "a1b2c3d4") → "main.a1b2c3d4.css"

func GetResource 

func GetResource(resources []engine.Resource, name string) *engine.Resource

GetResource returns the first resource matching the given name (exact match).

func IsImage 

func IsImage(name string) bool

IsImage returns true if the file extension indicates an image format.

func MatchResources 

func MatchResources(resources []engine.Resource, pattern string) []engine.Resource

MatchResources returns all resources whose Name matches the glob pattern.

func MediaTypeFromExt 

func MediaTypeFromExt(ext string) string

MediaTypeFromExt returns the MIME type for a file extension. The extension should include the leading dot (e.g., ".jpg").

func RenderPicture 

func RenderPicture(src, alt string, width, height int, variants []ImageVariant, lqip string, lazy bool, opts ...PictureOptions) string

RenderPicture generates HTML for a responsive <picture> element. If no variants are provided, falls back to a simple <img> tag.

func RenderSrcset 

func RenderSrcset(variants []ImageVariant) string

RenderSrcset generates the srcset attribute value from a list of variants.

func ResourcesByType 

func ResourcesByType(resources []engine.Resource, mediaType string) []engine.Resource

ResourcesByType returns all resources whose MediaType starts with the given prefix. For example, ResourcesByType(resources, "image") matches "image/jpeg", "image/png", etc.

func TransformCSS 

func TransformCSS(content string, minify bool) (string, error)

TransformCSS runs esbuild's Transform API on a raw CSS string. When minify is true, whitespace and syntax are minified. When minify is false, the input is returned unchanged.

Types

type BundleResult 

type BundleResult struct {
	OutputFiles []BundledFile
	Errors      []string
}

BundleResult holds the output of a bundle operation.

type BundledFile 

type BundledFile struct {
	Name         string // output filename (potentially fingerprinted)
	OriginalPath string // original entry point path as referenced
	OutputURL    string // URL path (e.g., "/assets/css/main.a1b2c3d4.css")
	Content      []byte
}

BundledFile represents a single bundled output file.

type Bundler 

type Bundler struct {
	Resolver  *Resolver
	DevMode   bool
	Minify    bool
	OutputDir string // absolute path to output directory
}

Bundler handles CSS/JS bundling and minification via esbuild.

func (*Bundler) BundleCSS 

func (b *Bundler) BundleCSS(entryPoint string) (*BundleResult, error)

BundleCSS bundles a CSS entry point, resolving @import through the 3-layer resolver.

func (*Bundler) BundleJS 

func (b *Bundler) BundleJS(entryPoint string) (*BundleResult, error)

BundleJS bundles a JS entry point, resolving imports through the 3-layer resolver.

type Cache 

type Cache struct {
	Dir string // e.g., {ProjectDir}/.cache/images
}

Cache stores processed asset results keyed by source hash + processing params. Entries are stored as JSON files in the .cache/ directory.

func NewCache 

func NewCache(projectDir string) *Cache

NewCache creates a cache rooted at {projectDir}/.cache/images.

func (*Cache) Get 

func (c *Cache) Get(key string) (*CacheEntry, error)

Get retrieves a cached entry. Returns nil if the entry does not exist.

func (*Cache) Key 

func (c *Cache) Key(sourceHash, params string) string

Key generates a cache key from a source hash and processing parameters.

func (*Cache) Put 

func (c *Cache) Put(key string, entry *CacheEntry) error

Put stores a processing result in the cache.

type CacheEntry 

type CacheEntry struct {
	SourceHash string         `json:"source_hash"`
	Params     string         `json:"params"`
	Variants   []ImageVariant `json:"variants"`
	LQIP       string         `json:"lqip"` // base64 data URI
}

CacheEntry holds cached image processing results.

type ImageOptions 

type ImageOptions struct {
	Op      ResizeOp
	Width   int
	Height  int
	Quality int
	Formats []string
}

ImageOptions controls per-image processing parameters. Zero values mean "use config defaults".

func ParseImageOptionsFromQuery 

func ParseImageOptionsFromQuery(s string) ImageOptions

ParseImageOptionsFromQuery parses a query string like "width=800&op=fill&format=webp" into ImageOptions. Used by the resize_image template function.

type ImageProcessor 

type ImageProcessor struct {
	Config  *config.ImageSettings
	Cache   *Cache
	DevMode bool
}

ImageProcessor handles image resize, LQIP generation, and variant production.

func (*ImageProcessor) ProcessImage 

func (p *ImageProcessor) ProcessImage(srcPath string, opts ImageOptions) ([]ImageVariant, string, error)

ProcessImage generates responsive variants and LQIP for a source image. Variant image files are saved to the cache directory (not the output directory). Use WriteProcessedImages to copy cached variants to the output directory after the writer runs. Returns variants, LQIP base64 string, and error. In DevMode, returns empty results (dimensions are already set by the enhancer).

func (*ImageProcessor) WriteProcessedImages 

func (p *ImageProcessor) WriteProcessedImages(outputDir string, trackFn func(string)) (int, error)

WriteProcessedImages copies all cached image variants to the output directory. Call this after the writer has cleaned and written HTML files.

func (*ImageProcessor) WriteProcessedImagesWithOptions 

func (p *ImageProcessor) WriteProcessedImagesWithOptions(outputDir string, trackFn func(string), opts WriteOptions) (int, error)

WriteProcessedImagesWithOptions copies all cached image variants to the output directory. Call this after the writer has cleaned and written HTML files.

type ImageVariant 

type ImageVariant struct {
	Width    int    `json:"width"`
	Height   int    `json:"height"`   // output height (computed from resize op)
	Format   string `json:"format"`   // "jpeg", "png", "webp"
	URL      string `json:"url"`      // output URL path
	FileSize int64  `json:"fileSize"` // bytes
}

ImageVariant represents a single processed image variant (width + format).

type Manifest 

type Manifest struct {
	// contains filtered or unexported fields
}

Manifest maps original asset paths to their output (potentially fingerprinted) paths.

func NewManifest 

func NewManifest() *Manifest

NewManifest creates an empty asset manifest.

func (*Manifest) Add 

func (m *Manifest) Add(original string, entry ManifestEntry)

Add registers an asset mapping in the manifest.

func (*Manifest) Len 

func (m *Manifest) Len() int

Len returns the number of entries in the manifest.

func (*Manifest) Lookup 

func (m *Manifest) Lookup(original string) (ManifestEntry, bool)

Lookup retrieves the manifest entry for an original asset path.

type ManifestEntry 

type ManifestEntry struct {
	OriginalPath string         // original asset path as referenced
	OutputPath   string         // relative to output dir (e.g., "assets/main.a1b2c3d4.css")
	OutputURL    string         // URL path (e.g., "/assets/main.a1b2c3d4.css")
	Hash         string         // content hash
	Variants     []ImageVariant // image variants (Phase 10b)
	LQIP         string         // base64 LQIP data URI (Phase 10b)
}

ManifestEntry maps an original asset path to its processed output.

type PictureOptions 

type PictureOptions struct {
	IncludeDimensions bool  // when false, omit width/height from <img>
	Widths            []int // configured widths for dynamic sizes attribute
}

PictureOptions controls optional rendering behavior for <picture> elements.

type Pipeline 

type Pipeline struct {
	// contains filtered or unexported fields
}

Pipeline orchestrates all asset processing.

func NewPipeline 

func NewPipeline(opts PipelineOptions) *Pipeline

NewPipeline creates and initializes the asset pipeline.

func (*Pipeline) BundleGlobalAssets 

func (p *Pipeline) BundleGlobalAssets() error

BundleGlobalAssets processes CSS/JS entry points from the site config (head.custom_css, head.custom_js). Bundled files are written to the output directory and registered in the manifest.

func (*Pipeline) EnhanceResources 

func (p *Pipeline) EnhanceResources(page *engine.Page) error

EnhanceResources populates resource metadata for a page's bundle assets.

func (*Pipeline) GlobalCSSURLs 

func (p *Pipeline) GlobalCSSURLs() []string

GlobalCSSURLs returns the output URLs of all CSS files bundled from head.custom_css.

func (*Pipeline) ImageProcessor 

func (p *Pipeline) ImageProcessor() *ImageProcessor

ImageProcessor returns the image processor for use in markdown rendering.

func (*Pipeline) Manifest 

func (p *Pipeline) Manifest() *Manifest

Manifest returns the asset manifest for template function use.

func (*Pipeline) OutputDir 

func (p *Pipeline) OutputDir() string

OutputDir returns the configured output directory.

func (*Pipeline) Resolver 

func (p *Pipeline) Resolver() *Resolver

Resolver returns the asset resolver for template function use.

func (*Pipeline) WriteBundleAssets 

func (p *Pipeline) WriteBundleAssets(pages []*engine.Page, outputDir string, trackFn func(string)) error

WriteBundleAssets copies bundle assets from their source locations to the output directory. If trackFn is non-nil, each written path is reported for orphan tracking.

func (*Pipeline) WriteBundleAssetsWithOptions 

func (p *Pipeline) WriteBundleAssetsWithOptions(pages []*engine.Page, outputDir string, trackFn func(string), opts WriteOptions) error

WriteBundleAssetsWithOptions copies bundle assets from their source locations to the output directory.

func (*Pipeline) WriteBundledFiles 

func (p *Pipeline) WriteBundledFiles(outputDir string, trackFn func(string)) error

WriteBundledFiles writes bundled CSS/JS files to the output directory. If trackFn is non-nil, each written path is reported for orphan tracking.

func (*Pipeline) WriteBundledFilesWithOptions 

func (p *Pipeline) WriteBundledFilesWithOptions(outputDir string, trackFn func(string), opts WriteOptions) error

WriteBundledFilesWithOptions writes bundled CSS/JS files to the output directory.

func (*Pipeline) WriteProcessedImages 

func (p *Pipeline) WriteProcessedImages(outputDir string, trackFn func(string)) (int, error)

WriteProcessedImages copies cached image variants to the output directory. If trackFn is non-nil, each written path is reported for orphan tracking. Returns the number of image variants written.

func (*Pipeline) WriteProcessedImagesWithOptions 

func (p *Pipeline) WriteProcessedImagesWithOptions(outputDir string, trackFn func(string), opts WriteOptions) (int, error)

WriteProcessedImagesWithOptions copies cached image variants to the output directory.

type PipelineOptions 

type PipelineOptions struct {
	ProjectDir string
	OutputDir  string
	Config     *config.SiteConfig
	ThemeName  string
	EmbeddedFS fs.FS
	DevMode    bool
}

PipelineOptions configures the asset pipeline.

type ProcessedImage 

type ProcessedImage struct {
	Src      string         // original/fallback src URL
	Alt      string         // alt text
	Width    int            // original width
	Height   int            // original height
	LQIP     string         // base64 data URI for blur-up placeholder
	Variants []ImageVariant // responsive variants with srcset
	Loading  string         // "lazy" or "eager"
}

ProcessedImage holds all data needed to render a responsive image.

type ResizeOp 

type ResizeOp string

ResizeOp specifies how an image should be resized. 

const (
	ResizeOpScale     ResizeOp = "scale"
	ResizeOpFitWidth  ResizeOp = "fit_width"
	ResizeOpFitHeight ResizeOp = "fit_height"
	ResizeOpFit       ResizeOp = "fit"
	ResizeOpFill      ResizeOp = "fill"
)

type Resolver 

type Resolver struct {
	ProjectDir string
	ThemeName  string
	EmbeddedFS fs.FS
}

Resolver implements 3-layer asset lookup: user assets/ → theme assets/ → embedded.

func (*Resolver) Resolve 

func (r *Resolver) Resolve(assetPath string) (string, error)

Resolve returns the absolute filesystem path for a named asset. Lookup order:

  1. {ProjectDir}/assets/{path}
  2. {ProjectDir}/themes/{ThemeName}/assets/{path}
  3. embedded FS assets/{path}

For embedded assets, returns "embedded:{path}" since there is no filesystem path.

func (*Resolver) ResolveContent 

func (r *Resolver) ResolveContent(assetPath string) ([]byte, error)

ResolveContent returns the file contents for a named asset. Uses the same 3-layer lookup as Resolve.

type ResourceEnhancer 

type ResourceEnhancer struct {
	DevMode bool
}

ResourceEnhancer populates Resource metadata for page bundles.

func (*ResourceEnhancer) EnhancePageResources 

func (e *ResourceEnhancer) EnhancePageResources(page *engine.Page) error

EnhancePageResources populates MediaType, Title, RelPermalink, Width, and Height for all resources attached to a page bundle.

type WriteOptions 

type WriteOptions struct {
	Parallel    bool
	WorkerCount int
}

WriteOptions controls bounded parallel asset writes.

Source Files

View all Source files

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.